1. Field of the Invention
The present invention relates generally to magnetic transducer heads and more particularly is directed to a magnetic transducer head for use in a perpendicular mode recording.
2. Description of the Prior Art
In carrying out the high density magnetic recording (short wavelength recording), it is known that the recording according to the magnetization in the thickness direction of a magnetic tape, namely, so-called perpendicular or vertical mode recording is more advantageous than the recording according to the magnetization along the relative moving direction of the magnetic tape to a magnetic transducer head or so-called longitudinal mode recording. The reason for this is that according to the longitudinal mode recording when the wavelength of the recording signal becomes shorter the self-demagnetizing field becomes larger, while according to the perpendicular or vertical mode recording the self-demagnetizing field within the magnetic layer becomes smaller.
As a magnetic transducer head employed in such perpendicular or vertical mode recording, there have been proposed various ones. In the perpendicular mode recording, in order to perform the ideal recording (magnetization), the main component of magnetic field from the magnetic transducer head must be made perpendicular to a magnetic record medium as much as possible. As such magnetic transducer head, there has been proposed, as shown in FIG. 1, an auxiliary magnetic pole excitation type magnetic transducer head h which comprises a main magnetic pole 102 made of, for example, permalloy thin film and an auxiliary magnetic pole 103, which are opposed to each other through a magnetic record medium 101 and in which a coil 104 is wound around the auxiliary magnetic pole 103.
In this case, however, the auxiliary magnetic pole 103 must be placed behind and close to the magnetic record medium 101 so that the practical assembling and the handling such as mounting the magnetic record medium 101 and so on become complicated.
In order to remove such defect, as shown in FIG. 2, there has been proposed such a recording system in which a magnetic record medium 101 formed of a magnetic layer 107 reinforced by a high permeability material layer 106 and formed on a nonmagnetic base 105 is used and in which such a main magnetic pole excitation type single magnetic pole transducer head h is used wherein auxiliary core 108 of high permeability is placed on one or both surfaces of main magnetic pole 102 at the position down from the top of the main magnetic pole 102, namely, at the position down from the contacting surface of the main magnetic pole 102 with the magnetic record medium 101 and the coil 104 is wound around the auxiliary core 108.
In the magnetic transducer head h of such kind, if the distance between the main magnetic pole 102 and the center of the coil 104 is taken as a, the length of the main magnetic pole 102 projecting from the auxiliary core is taken as b and the ratio a/b is selected in a range from 1 to 1.5 (a/b.perspectiveto.1.about.1.5), it was clarified that the good recording efficiency could be achieved experimentally and theoretically. Also, if the coil 104 is wound around the auxiliary core 108 at the position nearest to its top and the winding diameter thereof is reduced, the recording efficiency is made high and the impedance of the coil 104 can be lowered. The problem is how to make such transducer head in practice.